1. Field of the Invention
The present application relates to a fuel cell.
2. Discussion of the Background
For example, a solid polymer electrolyte fuel cell includes a solid polymer electrolyte membrane that is a solid polymer ion-exchange membrane. A unit cell of such a solid polymer fuel cell includes a membrane electrode assembly (MEA) (electrolyte electrode assembly) and separators (bipolar plates) that sandwich the membrane electrode assembly therebetween. The membrane electrode assembly includes a solid polymer electrolyte membrane and an anode electrode and a cathode electrode disposed on both sides of the solid polymer electrolyte membrane. Each of the anode electrode and the cathode electrodes includes an electrode catalyst layer and a porous carbon. Usually, a predetermined number of such unit cells are stacked to form a fuel cell stack, and the fuel cell stack is used, for example, for an automobile.
In a fuel cell stack of this type, a predetermined number (for example, several tens to several hundreds) of unit cells are stacked to obtain a desired power generation performance. Therefore, it is necessary to detect whether or not each of the unit cells has a desired power generation performance. For this purpose, a voltage detector (cell voltage monitor) is generally connected to a cell voltage monitor terminal of a separator, and the cell voltage of each of the unit cells or each of predetermined unit cells is detected by the voltage detector.
For example, a fuel cell described in Japanese Unexamined Patent Application Publication No. 2008-140722 includes a seal-gasket-integrated MEA 1 illustrated in FIG. 29. The seal-gasket-integrated MEA 1 includes a first MEA 1a and a second MEA 1b, each having a rectangular shape. A seal gasket 2 is disposed around the first and second MEAs 1a and 1b. 
A plurality of through-holes 3 for supplying and discharging hydrogen gas, air, and cooling water are formed in the seal gasket 2. The seal gasket 2 is provided with a seal line SL that extends around the first MEA 1a, the second MEA 1b, and the through-holes 3. A cell voltage monitor terminal 4 and a terminal line 5 are embedded in a corner of the seal gasket 2. A part of the cell voltage monitor terminal 4 protrudes from one of the surfaces of the seal gasket 2.